1. Field of the Invention
The present invention relates to a light-emitting element and a method for manufacturing the same.
2. Description of the Related Art
In a surface-emitting laser element, on a substrate, for example, an active layer having a multiple quantum well structure is disposed in a cavity sandwiched between two mirror layers provided on upper and lower sides thereof, light emitted from the active layer under current injection is confined, and thus laser oscillation is caused. In such a surface-emitting laser element, a cylindrical mesa structure is usually employed, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 2005-026625. Specifically, for example, a cylindrical mesa structure with a diameter of about 30 μm is formed by dry etching or the like. Alternatively, as disclosed in each of Japanese Unexamined Patent Application Publication Nos. 11-150340 and 2004-319553, a mesa structure surrounded by a protrusion is formed. These mesa structures each have, for example, a laminate structure including an n-type compound semiconductor layer, an active layer, and a p-type compound semiconductor layer. By oxidizing a part of the p-type compound semiconductor layer from the sidewall portion of the mesa structure, a current constriction region is provided in the center of the p-type compound semiconductor layer. Then, the mesa structure is coated with an insulating layer, a part of the insulating layer on the top face of the p-type compound semiconductor layer is removed, and a ring-like p-side electrode is formed on the periphery of the top face of the p-type compound semiconductor. In addition, an n-side electrode is formed on the back face of the substrate. By providing such a current constriction region, current can be injected with high efficiency into the active layer. In the surface-emitting laser element having such a structure, current is efficiently injected into the active layer, and highly efficient laser oscillation can be obtained.
A mesa structure is usually formed using photolithographic and etching techniques. Furthermore, when a current constriction region is formed, a p-type compound semiconductor layer is often oxidized in a high-temperature water vapor atmosphere. The oxidizing treatment is controlled by adjusting the time for which the p-type compound semiconductor layer is exposed to the high-temperature water vapor atmosphere. Furthermore, a p-side electrode is usually formed using photolithographic and etching techniques or a lift-off technique.